1. Field of the Invention
This disclosure relates to an apparatus for fabricating a display device, and more particularly to an apparatus for fabricating a display device that is adaptive for improving reliability.
2. Discussion of the Related Art
A liquid crystal display device is a type of a flat display device that displays an image by use of liquid crystal, and is widely used because of its advantages, including that it is thinner than other display devices and its power consumption is low.
The liquid crystal display device includes a liquid crystal display panel for displaying an image, and a backlight unit for supplying light to the liquid crystal display panel.
In general, the liquid crystal display panel is formed in a structure that a liquid crystal layer is interposed between substrates which face each other.
The fabrication process of the liquid crystal display panel includes a thin film deposition process of forming a thin film at the surface of a substrate, a photo lithography process of exposing a selected part of the thin film, an etching process of patterning it to remove the exposed part of the thin film, and various processes such as cleaning, bonding and cutting. And, the thin film deposition process, the photo lithography process and the etching process are repeated several times before being completed
After cleaning the patterned substrate, a process of applying heat to the substrate while keeping the substrate in a vacuum state is carried out in order to eliminate moisture and impurities on the patterned substrate.
The process of applying heat to the substrate in the vacuum state is carried out with a vacuum heating device.
The vacuum heating device has a heating source within a chamber and the substrate is transferred into the chamber in the vacuum heating process.
The inside of the chamber has a high temperature environment in the vacuum state so that the moisture or impurities on the substrate could be removed, and a vent gas is supplied from the outside for the inside of the chamber to have the atmospheric pressure of the outside. And then, the substrate is transferred to the outside.
However, the general vacuum heating device has a problem in that, when the vent gas is injected into the chamber of a temperature of 100 degree centigrade in order to change the vacuum state to a normal atmospheric pressure, moisture is condensed on the surface of the substrate by the instantaneous temperature difference as the vent gas of the low temperature (below around 25 degree centigrade) is supplied from the outside into the chamber of the high temperature.
Also, the general vacuum heating device has a problem in that a vent gas outlet is clogged when used for a long time because the moisture or impurities vaporized from the substrate are adhered at a gas outlet area, through which the vent gas is supplied into the chamber, by the instantaneous temperature difference caused by the vent gas supply.